The sonograms were performed by the same sinologist (L-J Liao) using an ATL HDI 5000 with a high-resolution 7.5- to 12-MHz real-time linear-array transducer (Philips Ultrasound, Bothell, WA, USA). Morphological US parameters were thoroughly evaluated and recorded on the Marosis PACS system (Marotech Inc., Seoul, South Korea). The lengths of short and long axes of enlarged lymph nodes were measured and recorded. The shape of the lymph node was determined by the short axis to long axis ratio (S/L ratio). The nodal border was assessed for sharpness. Echogenicity of the lymph nodes was compared with that of adjacent muscles. Swelling of the surrounding tissues that presented with hyperechoic rims was assessed. The nodes were considered matted when a number of lymph nodes were clustered together. The internal architecture of lymph nodes was examined for the presence of heterogeneous micronodular pattern or reticulation.